The amazing world of LEGO® Technic constructions.
Based on the vision from Ole Kirk Christiansen (1891-1958), a carpenter from Billund/Denmark, whose personal motto was "Only the best is good enough" - Leg Godt (Play Well).

TechnicBRICKs blog (TBs hereafter) is devoted to the LEGO Technic theme and intends to spot mainly on news and developments, rather than new sets reviews or users creations (aka MOCs). However you will also find them here occasionally...

Monday, October 6, 2008

While browsing Parax’s Brickshelf folder, I found something worth heeding for every TECHNIC inventor: examples of dead ends you won’t want to get yourself into.

There are some combinations of parts you can put together, but are nigh-impossible to take apart. Take a look at Parax’s examples (and note that he wisely didn’t use physical pieces!), to see for yourself what horrors these seemingly innocuous structures hide. As you can see, building any one of these is easy, if the axles (in grey in the first example, and red in the second) are the last pieces to be added.

But disassembling them is another story... In both examples, you would be able to disassemble the structure if somehow you could pull out the axles again. But they’re fully inserted, without any protruding bit to grab and pull, and the Angle Connectors #2 don’t allow then to be pushed to come out at the other side. Also, on the first example, if you could rotate the Axle Joiners Perpendicular free from the Pins Long with Friction, none of this would have happened. But it can’t be done without breaking either the joiners, the pins, or both.

So, if you really need to have a structure like these or similar, how can you avoid this nasty deadlock?

First of all, you can give yourself somewhere to grab and pull, by using longer axles that stick a bit out of the structure. Given the friction axleholes impose, maybe one extra stud isn’t enough, unless you use potentially damaging tools like pliers; just to be on the safe side, the best would be to use 5L axles on the first example and 4L axles on the second.

Also, on the first example you can replace the long pins with axles (properly bushed at each end), so that you can push or pull them out.

But it seems Alexandre used mostly the original images from Parax instead of preparing new ones, despite he reproduced one of them to present alternatives.So he would need just to do also the LDRAW model for the turntable setup.

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Another topic that was in my queue... :)But I think I'll add soon another one with a few more examples, although not so different, I found in BS.

There, all pictures have now transparent backgrounds. :) When I made the three "solution" pictures, I indeed had them with transparent backgrounds, but decided to change them back to black to match Parax's pictures.

rick-sam: That's indeed luck! I never imagined an exacto knife's blade would be strong enough to pull an axle from inside an axlehole... I guess a nicked axle is still better than a bunch of ruined parts.

Oh dang, changing the background to transparent was easy, but changing part colours? Besides, I used black for the turntable alternative because that's the "natural" colour for 4T axles. But OK, I'll re-download the whole bunch of files and subfiles for the unofficial LDraw turntable file, turn it the upside down (to make the dark grey half make more contrast with the black axles), and rebuild the picture...

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